iOS players have been taking to Twitter to voice concerns about Game Center breaking when attempting to play games, specifically Letterpress.

Letterpress is a fairly new word game for iOS devices. It relies on Game Center's connectivity that allows you to play against your friends, sending notifications as to whose turn is next while tracking leading scores. Letterpress may very well not be the only culprit in Game Center's bugginess, but it's certainly the focal point for some of Twitter's most vocal gaming crowd. One player even mentioned it on the app's official page:

Great game killed by Game Center

by Gavin McKeown

This is a great game with a simple concept and endless gameplay. Unfortunately the playing experience is completely ruined by Game Center (which my phone insists on capitalizing). Here's a hint Apple: put more money into having Game Center cope with high load rather than capitalizing your trademark.
A lot of waiting for GC to update games. A lot of "Error -1001" failures. Badges on the app icon that don't relate to the game content. The list goes on. I never used GC before (as I suspect a lot of users didn't) and now it will go back to the last screen of baked in un-deletable apps and my $0.99, unlocked version of Letterpress will join it.
5 stars for the gameplay and concept
Negative stars for the Game Center back end.

Some players have specifically noted an error message (Error 1001) suggesting that Game Center is to blame:

@zipties Also, there appears to be a Game Center bug where game invitations go bad (the inviter “loses” the game after playing one turn).

And our own Owen Good noted that, "GameCenter was jamming up Totem Runner today. Extremely chunky and lagging."

I've been playing around with Letterpress and Game Center today, and while I haven't seen any error messages or crashes, I have experienced some lag between notifications for friend requests, turns (though not always), etc. Let us know if you've been experiencing anything similar.

I've reached out to Letterpress' developers—atebits—and will update should they respond.